How to grow finger lime in Australia

Finger lime is a warm-climate citrus, frost-tender when young, and best planted in the warmer months once frost has passed.

Subtropical (Brisbane, northern NSW): The heartland. Plant in spring and it will grow in the ground in a warm, part-shaded to sunny spot, much as it does in its native border-ranges rainforest.

Warm temperate (Sydney, Perth, Adelaide): Plant in spring in a sheltered, warm position. It grows well but more slowly than up north, and young plants need frost protection.

Cool temperate (Melbourne): Best grown in a pot you can move under cover for winter. Choose the warmest microclimate and be patient.

Cold (Hobart, Canberra, alpine): Too cold for open ground. Grow in a container and overwinter it in a glasshouse or bright, frost-free indoor spot.

Tropical (Cairns, Darwin): Grows readily, though it appreciates some relief from the most intense sun and humidity. Plant at the start of the warmer, drier stretch.

Arid (Alice Springs): Only with afternoon shade and steady water. The dry air and heat extremes are harder on it than on tougher citrus.

Buy a grafted plant rather than growing from seed. Grafted finger limes fruit years sooner and are far more reliable. Plant into free-draining soil improved with compost, keeping the graft union above the soil, and mulch well while keeping the mulch off the trunk.

Be patient with establishment. Finger lime is naturally slow and can take two to four years to fruit well. Feed with a citrus fertiliser in late winter and summer, water it in thoroughly, and shelter young plants from frost and harsh wind while they settle.

Finger lime suits pot culture, which is how most gardeners south of the subtropics grow it. Use a large, free-draining pot and a quality mix, and enjoy being able to move it into sun in summer and under cover in winter.

In the ground, in a frost-free garden, it makes a dense, very thorny shrub to around two metres. That thorniness makes it a decent informal barrier, but plan your picking access. A warm, sheltered spot with morning sun and some afternoon protection mimics its rainforest-edge origins.

Give it a bright position with five or more hours of sun, but note that as a rainforest-margin plant it appreciates a little relief from the harshest afternoon sun, especially in hot inland gardens. In cool districts, maximise warmth and shelter.

Water regularly and deeply, particularly in pots, and never let it dry out completely while fruiting. As with all citrus, it dislikes waterlogging, so free-draining soil and consistent, moderate moisture is the balance to aim for.

Fruit ripen in autumn and into winter, usually two to three years after planting a grafted tree, and longer from seed. The fruit is ready when it comes away from the stem with a gentle twist and the skin has taken on its mature colour, which varies from green to pink, red or almost black depending on the selection.

Harvest carefully around those thorns. Pick fruit as it ripens rather than all at once, and squeeze the pearls out fresh, since they are at their best used straight away as a garnish over seafood, salads and desserts.

Finger lime gets the standard citrus pests: citrus leaf miner on new growth, citrus gall wasp, scale, aphids and sooty mould. Manage them with horticultural oil, pruning out galls, and encouraging beneficial insects. Position matters too, as a stressed, cold or waterlogged plant is far more prone to trouble.

Frost is the main killer of young plants, so protect them through their first winters in cooler zones. As a citrus, foliage and oils can mildly upset pets that chew a lot of it.

Like other citrus, finger lime benefits from flowering companions such as borage and nasturtium nearby to attract pollinators and beneficial insects, and from a cool, weed-free root zone. Keep vigorous shrubs and grass back from the base so it is not competing for water and nutrients, and give it room to spread its thorny frame.

How long until a finger lime fruits?

A grafted plant usually takes two to three years to fruit well, and seed-grown plants much longer. Finger lime is naturally slow, so patience and a warm, sheltered spot pay off.

Can I grow finger lime in Melbourne or Hobart?

In a pot, yes. It is frost-tender, so grow it in a container you can keep in the warmest spot over summer and move under cover through winter.

Why is my finger lime so thorny?

Thorniness is natural for the species, especially on younger and more vigorous growth. Plan your picking access, and prune lightly to keep fruit within reach.